/*
 * Copyright (c) Kumo Inc. and affiliates.
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cstddef>
#include <type_traits>
#include <utility>

#include <melon/utility.h>
#include <melon/lang/align.h>

namespace melon {
    template<typename T, std::size_t Align>
    class aligned {
        static_assert(!(Align & (Align - 1)), "alignment not a power of two");
        static_assert(alignof(T) <= Align, "alignment too small");

    public:
        using alignment = index_constant<Align>;
        using value_type = T;

        aligned() = default;

        aligned(aligned const &) = default;

        aligned(aligned &&) = default;

        template<
            typename S = T,
            std::enable_if_t<std::is_copy_constructible<S>::value, int>  = 0>
        aligned(T const &value) noexcept(std::is_nothrow_copy_constructible<T>::value)
            : value_(value) {
        }

        template<
            typename S = T,
            std::enable_if_t<std::is_move_constructible<S>::value, int>  = 0>
        aligned(T &&value) noexcept(std::is_nothrow_move_constructible<T>::value)
            : value_(static_cast<T &&>(value)) {
        }

        template<
            typename... A,
            std::enable_if_t<std::is_constructible<T, A...>::value, int>  = 0>
        explicit aligned(std::in_place_t, A &&... a) noexcept(
            std::is_nothrow_constructible<T, A...>::value)
            : value_(static_cast<A &&>(a)...) {
        }

        aligned &operator=(aligned const &) = default;

        aligned &operator=(aligned &&) = default;

        template<
            typename S = T,
            std::enable_if_t<std::is_copy_assignable<S>::value, int>  = 0>
        aligned &operator=(T const &value) noexcept(
            std::is_nothrow_copy_assignable<T>::value) {
            value_ = value;
            return *this;
        }

        template<
            typename S = T,
            std::enable_if_t<std::is_move_assignable<S>::value, int>  = 0>
        aligned &operator=(T &&value) noexcept(
            std::is_nothrow_move_assignable<T>::value) {
            value_ = std::move(value);
            return *this;
        }

        T *get() noexcept { return &value_; }
        T const *get() const noexcept { return &value_; }
        T *operator->() noexcept { return &value_; }
        T const *operator->() const noexcept { return &value_; }
        T &operator*() noexcept { return value_; }
        T const &operator*() const noexcept { return value_; }

    private:
        alignas(Align) T value_;
    };

    template<typename T>
    using cacheline_aligned = aligned<
        T,
        (cacheline_align_v < alignof(T) ? alignof(T) : cacheline_align_v)>;
} // namespace melon
